biology essay

Poliomyelitis Eradication In Nigeria Biology Essay

Published: 23, March 2015

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Poliomyelitis is a virus that is spread by the oral fecal route mainly in children under five via water contamination and contact with various other contaminated fomites. Most children display no symptoms while others may have symptoms usually associated with gastrointestinal infections. Symptoms may include headache, fever, malaise, and vomiting but in severe cases, less than 1 percent of people experience paralysis. In the United States polio became prevalent in the 1950s during the summer months, today the use of the polio vaccines has lead to rare to non-existent polio cases. The Salk inactivated polio vaccine was introduced to the US in 1955. This vaccine is a fixed vaccine injection that uses inactivated or purified polio virus antigens and causes no risk of disease. In 1961 another vaccine was produced for polio which is called the Sabin oral vaccine. This oral vaccine is an attenuated vaccine that causes viral replication in the body and is shed in the stool for up to six weeks. After usage in the US these vaccines were shipped internationally to aid in vaccination, specifically the oral vaccine is used because it is cheap and easily administered. Although these oral drops are more convenient it has also been associated with vaccine paralytic polio (Frey Gastro-Intestinal). At times the oral vaccine can induce polio within a person's body or activate a mutant wild virus of the original virus creating a worse and deadly virus, but vaccination is important in order to protect unimmunized people. Particularly in northern Nigeria near Kano polio has been a rampant disease that has left thousands of children paralyzed over the years. The World Health Organization (WHO) has had to fight myths about the vaccine and encourage Nigeria to participate in the global effort to eradicate the disease. Polio is a disease that has a vast replication and life cycle, can result in a paralysis, and has continued to be endemic to many countries internationally, specifically Nigeria (WHO).

Poliovirus is 7 kilo bases and is apart of the enterovirus genus and the picornavirus family. It is a single stranded (ss) positive RNA virus. It consists of a naked icosahedral capsid and a non-segmented genome. Poliovirus has three serotypes that can infect the cell (Frey RNA). When undergoing attachment the polio binds to the poliovirus receptor (PVR). Binding creates a conformational change in the viruses' capsid which initiates uncoating. Polio enters the cell by endocytosis and migrates to the lining of the intestine being that is has specific tissue tropism for this part of the body. It can also migrate to the nerve tissue which will result in paralytic poliomyelitis. Uncoating proceeds and poliovirus genetic material is secreted into the cytoplasm. Poliovirus initiates uncoating by directly entering the cell, binding PVR, and injecting the genome into the cell cytoplasm. Another method that can be used when uncoating is receptor-mediated endocytosis. When receptor-mediated endocytosis occurs uncoating takes place inside a compartment that the cell forms and the genome is released into the cytoplasm (Dove). Synthesis proceeds and the viruses' 5' internal ribosome entry site which is cap-less uses its viral protein genome that is used to prime RNA before synthesis. From there poliovirus's one 1-10 5' open reading frame polyprotein precursor is cleaved by protease into smaller sub genomic RNA that can be translated to make mature proteins by RNA dependent RNA polymerase. The viral RNA is used as messenger RNA and is translated directly. Asymmetric synthesis occurs and more positive ss RNA are needed so the virus replicates. When undergoing replication replicase proteins use positive strand RNA template to make complementary negative strand ssRNA by using RNA dependent RNA polymerase. From there negative strand complement is made into positive strand ssRNA which is a copy of the original genome. Lastly, it is translated to make mature proteins (Frey RNA).

The virus enters the host by contaminated drinking water, contaminated surfaces, and lack of hand washing. It passed through the stomach and reaches the intestine where it establishes itself into the intestinal lining replicating and infecting cells (Dove). Once infected diarrhea-like symptoms occur including headache, malaise, vomiting, and fever this can be classified as abortive poliomyelitis. Symptoms usually last 3 days, the nervous system is not involved and victims make a full recovery. When infected people display symptoms such as back pain and neck stiffness this is called aseptic meningitis and is a result from the poliovirus. However, in more serious causes, 1 percent of infected people experience flaccid paralysis which is paralytic poliomyelitis. Even more severe cases may have cranial nerve paralysis and respiratory muscle damage. When the virus enters the bloodstream it migrates to the nervous systems deteriorating motor neurons that control movement and cause paralysis or lead to death. Bulbar polio is an example of this in which polio reaches the brainstem causing impairment in breathing, speaking, and swallowing which can lead to death. 25 percent to 40 percent of polio survivors experience post polio syndrome. This occurs 30 to 40 years after the first initial exposure to polio. Damaged neurons in muscles are weakened from the initial infection and victims experience fatigue and joint pain (Flynn).

In the laboratory cytopahtic effect (CPE) was observed on various cells. In diploid cells infected with Sabin polio virus early and late CPE at 125X magnification displayed detachment and cell degeneration. On Hep-2 cell lines early and late CPE at 125X magnification displayed detachment. In primary rhesus monkey kidney cells early and late CPE at 125X magnification displayed detachment and syncytia (Pan American Society). These findings lead scientists to come to a conclusion about polio and it's degradation on the cells. When cells were infected with polio they were severely damaged.

Once a person is infected with polio there is no treatment, doctors can only alleviate symptoms because there have been no effective antivirals. Motor nerve damage cannot be repaired and paralysis is permanent. Prevention is the key in order to prevent polio from entering the body and becoming infected. Proper sanitary conditions and vaccinations can aid in the transmission of polio. Since polio is typically spread through water sources, clean water systems could drastically cut transmission. However, person to person contact would still be a problem. Once a person is infected and takes the disease back to their community unimmunized people are at risk (Flynn). Currently there are two vaccines used in the prevention of poliovirus. The Salk inactivated polio vaccine consists of three serotypes and is given through injection. The virus is grown on Vero cells and inactivated with formaldehyde. This vaccine stimulates an IgG response and after three doses is 99% affective against disease. Since this vaccine contains an inactivated form of polio the span of immunity is not known. The Sabin oral vaccine which consists of oral drops also contains three serotypes of poliovirus and is grown on Vero cells. After administered, the virus is shed in the stool for up to six weeks. Since this vaccine contains live virus vaccine associated paralytic polio (VAPP) is a risk. The virus can mutate to a more deadly from causing permanent damage (Frey Gastro-Intestinal).

In 1988 the World Health Assembly had an annual meeting of all the various ministers and members of health of the WHO. They voted to eradicate polio and launch the Global Polio Eradication Initiative. This goal was set out to proceed with vaccination of their population in order to ensure the eradication of the poliovirus. Their primary objective was aimed at international countries who every year seemed to have thousands of cases of polio (WHO). When this decision was made Nigeria initially signed on but was conflicted. For years myths circulated about the vaccines given by the Western world. They believed that this was the Western's world's plan to sterilize Africans or give them AIDS. In 1996 polio was widespread in 41 African countries. 75,000 African children were being paralyzed every year. Until 2002, many southern states of Nigeria were polio free. Although polio was a high-risk problem at the time, in 2003 Nigerian leaders suspended the polio vaccine believing it would sterilized their children and infect them with HIV. They exported nearly two dozen shipments of the vaccine to countries worldwide. In 2004 they resumed with vaccination after tests showed the vaccine was not contaminated with any agents (Dugger, WHO).

In Nigeria children under the age of 5 are the most susceptible. One child infected with the virus can infect a whole community and village leaving unimmunized people at risk for contracting polio. Over the years various immunization days have been coordinated throughout Nigeria in order to target a large amount of children (WHO). On February 4th, 2010 in Abuja, the new bivalent polio vaccine (bOPV) was brought to Nigeria in order to target 53 million children under the age of 5. In 2008 there were 782 cases of polio while in 2009 there were 388 cases of polio. As of February 2010 there have been fewer than 30 new cases of polio. Nigeria is the first African country to receive the bOPV vaccine. This vaccine had been proved to work efficiently against poliovirus type 1 and 3 which is the wild poliovirus that remains endemic to the country. In northeastern Nigeria in Zamfafa state there is a remote community Gummi which is the most high risk area and has a record of low children that are immunized within the state. There are a large number of unimmunized children so they are more prone to polio outbreaks. Through the use of spiritual leaders of Nigeria's Muslim community, political and traditional leaders have made an impact on improving turnout of immunization. They have stuck with the commitment Nigeria has made to end polio within the country. Within this state in 2009 they reported 13 children who had been infected with polio which resulting in paralysis. When they investigated these cases they saw that the virus was active in farming populations, border regions, and communities by rivers (UNICEF).

Through the cooperation with the WHO, United Nations Children's Fund (UNICEF), The Bill Gates Foundation, Centers for Disease Control (CDC), and various other organizations Nigeria has received a substantial amount of money that will aid in the eradication of polio within the country. Polio is more widespread in the north so the uses of traditional and political figures are needed in order for parents to bring their children on national vaccine days so that their children can be protected against the disease. The more children that are vaccinated the more protected communities, villages, and states will be working towards the goal of eradicating polio.

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